The Ethernet technique, simple and familiar to users, originates from the Local Area Network (LAN). Moreover, the Ethernet is a standard technique with good interoperability, support from wide software and hardware, and low cost. Meanwhile, it is a media-independent bearer technique which may interface with different transmission medium such as the twisted pairs, cable and various optical fibers, thereby avoiding the cost of rewiring. Therefore, the Ethernet networking technique is being significantly developed, and is becoming the bearer network for the Metro Area Network (MAN).
However, for the operable telecom-level Metro Ethernet, there are many problems to be solved regarding the architecture, network management, protection technique, Quality of Service (QoS) technique, as well as the service provision. With respect to the service protection, the Ethernet is originally designed for the internal applications for LAN users, without guarantee from a security mechanism. After it is extended to the telecom-level Metro Ethernet, a more reliable security mechanism is required in order to provide the reliability guarantees for the telecom services within the MAN. The Ethernet may be applied in the Metro telecom network environment as a telecom-level multi-service platform only if the major problem above is solved properly.
The conventional techniques involved in the present invention are briefly illustrated below.
1. Multi-Protocol Label Switching (MPLS) Technique
The MPLS belongs to the network architecture of the 3rd generation, and is a high-speed IP backbone switching standard of the new generation proposed by the Internet Engineering Task Force (IETF). The MPLS is a switching technique with the Layer 3 route incorporating the Layer 2 attributes, and introduces a label-based mechanism, in which the routing and data forwarding are separated and the path by which a packet passes through the network is specified by the label.
2. Virtual Private LAN Service (VPLS) technique
The VPLS is a service providing a similar LAN on the MPLS network. The VPLS enables users at dispersed geographical locations to access the network simultaneously and access each other, as if these locations are connected to the LAN directly. The VPLS enables the users to extend their LANs to the MAN, even to the Wide Area Network (WAN).
3. Virtual Router Redundancy Protocol (VRRP) technique
Generally, all the hosts in an internal network are configured with the same default route, pointing to the export gateway, thereby implementing the communications between the hosts and the external networks. If the export gateway is in fault, the communications between the hosts and the external networks will be interrupted. It is a common method to configure multiple export gateways in order to improve the system reliability. However, the routing among the multiple export gateways becomes a problem to be solved. The VRRP is a fault-tolerant protocol, in which the implementation of the physical devices and logical devices is separated and the default gateway of the terminal IP device is redundancy backed up, so that a standby router will take over the forwarding work upon one router is out of work, thereby providing transparent switching to the user, and solving the problem noted above properly.
In the conventional art, the services deployed on the Metro Area Network generally include many types of services, such as the Internet service, Virtual Private Network (VPN) service, Broadcast TV (BTV) service, and Video on demand/Voice over IP (VOD/VOIP) service. In the practical networking, the network architecture includes a backbone layer, and a convergence & access layer. Service Routers (SRs) are deployed at the network edge of the backbone layer and the convergence & access layer to implement the functions, such as the MAN service control, user control, and security control. Generally, in order to ensure the reliability of the network, the network service routers are disposed in an active-standby manner, so that the standby device starts to operate upon the active device is in fault, thereby ensuring that the network service will not be interrupted.
For the Layer 3 network services, such as the VOD, VOIP, and Layer 3 VPN, the VRRP protocol may be configured between the active and standby service routers, so that the related services may be switched to the standby service router when the network is in fault or the active service router is in fault. However, the VRRP is a Layer 3 network protocol not applicable for Layer 2 services, such as the internet (PPP access) service, and Layer 2 VPN service. Thus, when the network is in fault or the active service router is in fault, there is no highly effective protection method to switch the Layer 2 services for users to the standby service router quickly. In the conventional technique, the Layer 2 service switches to the path of the standby router with a Spanning Tree Protocol (STP) algorithm. However, the STP algorithm has a relatively long convergence time, which may not satisfy the requirement of rapid switching of network services. Accordingly, a disadvantage of the conventional technique is the lack of an effective, rapid and reliable redundancy standby mechanism for Layers 2 and Layer 3 services.